Re: Dealing with slow USB disks, was: Re: Saving environment variables in u-boot

Coming back to the saving of u-boot environment variables,
backing down to a much older set of FAT files seems to help.

The machine now has a DOS-only microSD with an old set of
files:

root@pelorus:/mnt # strings start.elf | grep "VC_BUILD_ID_"
VC_BUILD_ID_USER: dc4
VC_BUILD_ID_TIME: 15:31:38
VC_BUILD_ID_BRANCH: master
VC_BUILD_ID_TIME: Jun  7 2018

With this suite of bootfiles it's possible to save a value for
usb_pgood_delay of 19000, which in most cases results in a hands-
off detection of the usb hard disk (via a powered hub):

MMC:   mmc@7e300000: 1
Loading Environment from FAT... OK
In:    serial
Out:   vidconsole
Err:   vidconsole
Bus usb@7e980000: scanning bus usb@7e980000 for devices... 6 USB Device(s) found
       scanning usb for storage devices... 1 Storage Device(s) found
Hit any key to stop autoboot:  0

Intervention with run bootcmd_usb0 gives a successful boot from USB. 
If nothing is touched, the console displays: 

MMC Device 0 not found
no mmc device at slot 0
switch to partitions #0, OK
mmc1 is current device
Scanning mmc 1:1...
Found EFI removable media binary efi/boot/bootaa64.efi
BootOrder not defined
libfdt fdt_check_header(): FDT_ERR_BADMAGIC
Consoles: EFI console
    Reading loader env vars from /efi/freebsd/loader.env
Setting currdev to disk0p1:
FreeBSD/arm64 EFI loader, Revision 1.1

   Command line arguments: loader.efi
   Image base: 0x39e91000
   EFI version: 2.80
   EFI Firmware: Das U-Boot (rev 8217.4096)
   Console: comconsole (0)
   Load Path: /efi\boot\bootaa64.efi
   Load Device: /VenHw(e61d73b9-a384-4acc-aeab-82e828f3628b)/SD(1)/SD(0)/HD(1,0x
01,0,0x81f,0x18fa8)
Trying ESP: /VenHw(e61d73b9-a384-4acc-aeab-82e828f3628b)/SD(1)/SD(0)/HD(1,0x01,0
,0x81f,0x18fa8)
Setting currdev to disk0p1:
Trying: /VenHw(e61d73b9-a384-4acc-aeab-82e828f3628b)/SD(1)/SD(0)/HD(2,0x01,0,0x1
97c7,0x7726839)
Setting currdev to disk0p2:
Startup error in /boot/lua/loader.lua:
LUA ERROR: cannot open /boot/lua/loader.lua: no such file or directory.

Type '?' for a list of commands, 'help' for more detailed help.

It looks like the root device is still the microSD card, even though
the USB disk has been found. Any suggestions appreciated. There's a
complete and recent ports tree if it's helpful, attempts to use it 
on my own have caused more trouble than they've solved, in particular
that's what lead to the "saving to FAT....FAILED" messages. .  

Thanks for reading,

bob prohaska